Complex Family Trees, Genetic Genealogy Mark the Last of the Finalists in 2020 DNA Hit of the Year Program

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 Complex Family Trees, Genetic Genealogy Mark the Last of the Finalists in 2020 DNA Hit of the Year Program

Last week, Forensic revealed a daring and complex Brazilian robbery as the 2020 DNA Hit of the Year, as well as the murder of a toddler and infant as the second and third finalists, respectively.

The last pieces of the finalist puzzle for the 2020 DNA Hit of the Year come from China, Washington and California.

4th Place: Mother-Daughter Double Homicide

A man motivated by the theft of seemingly expensive belongings maliciously murdered a famous woman and her 20-year-old daughter, who was studying to become a doctor, in their apartment in a high-end residential community. More than 10 years after the 2018 crime, an illicit affair three decades earlier—and impeccable autosomal STR analysis—turned out to be the key to solving the cold case.

A mother and daughter were found murdered with a knife in their apartment in the wealthy Tianhe District of Guangzhou, China. The crime scene was thoroughly cleaned after the murder, but forensic experts were able to confirm the presence of two male suspects through DNA examination of the limited blood stains. Suspect A left multiple stains at the scene, but Suspect B left only a drop of blood on the foot of the youngest victim.

While none of the blood stains triggered a DNA match in 2008, Suspect B’s drop of blood did register a hit 11 years later. In 2019, investigators matched Suspect B’s DNA to DNA evidence for an unrelated burglary case through China’s Y-STR database. Between 2010 and 2020, it is estimated that China has added 10 million YS-TR profiles to its national DNA database.

In this case, there was a match between Suspect B and a burglary ex-con named Jun, but it was not direct. Jun was the only son of his parents, and further analysis of male cousins and uncles showed patrilineal similarities but not an autosomal genotype match to Suspect B.

Further analysis of 40 autosomal STR confirmed Jun and Suspect B were half-siblings through their mother, Xiu, who provided a DNA sample. Investigators then speculated that Suspect B’s biological father could be Jun’s paternal grandfather, Lin, who has died years earlier.

“Based on the genotype of Jun’s father and uncles, we worked backward to speculate on the possible genotype of Lin. Together with the known biological mother Xiu and Suspect B, 35 autosomal STR loci of three people showed a trio’s match. In conclusion, the suspect consists a paternity relationship with Xiu and Lin as his biological parents.”

Further investigation confirmed that, more than 30 years ago, Xiu and her partner’s father had an illegitimate child—who was abandoned, adopted by another family, and then murdered a woman and her daughter later in his life. The Chinese task force deduced Suspect B was married and worked in Malaysia. They intercepted his flight plan and arrested him at Changsha Hunan airport, where he confessed to the crime and revealed the identity of his partner.

5th Place: First Known Instance of Genetic Genealogy for Cold Case Lead

Genetic genealogy has undoubtedly revolutionized forensic work, making its largest impact in cold case investigations. Investigations that have been cold for upward of 30 years with little to no evidence are now being solved within weeks or months. In recognition, Gordon Thomas Honeywell selected genetic genealogy pioneer Colleen Fitzpatrick and her work on the case of Sarah Yarborough as the fifth finalist in the 2020 DNA Hit of the Year program.

In 1991, 16-year-old Sarah Yarborough was sexually assaulted and murdered on the grounds of her high school. The murder of the blonde All-American girl sent a chill through the small community. Although ample DNA was left at the crime scene by the assailant, there were no hits in CODIS. In 2011, further analysis compared the Y-STR profile of the crime scene DNA to public Y-STR genetic genealogy databases. This yielded a possible last name of the murderer, whose lineage could be traced back to Robert Fuller of Salem, Massachusetts in the 1630s, a relative of the Mayflower Fullers.

Suspicion fell on William Fuller, whose daughter Elizabeth Fuller, was a classmate of Yarborough’s. However, a voluntary DNA sample determined he was not the killer nor the father of the murderer. He was a paternal cousin of the killer—but that information was not enough and the case went cold again.

Then, in 2019, King County Detective Kathy Decker initiated a request to have the killer’s DNA processed for genetic testing and ancestral analysis. Fitzpatrick and her team at Identifinders International narrowed the suspect field down to two brothers, one of whom was a registered sex offender with his DNA in CODIS. The other did not have DNA in the system, so he was followed and cast-off DNA from cigarette butts was obtained. It matched the DNA at the Yarborough crime scene.

“Although the case was accepted by an independent lab as part of a pilot study to use autosomal SNP testing in 2014, the type of SNP analysis that was available to the forensic community at that time was primitive compared to the direct-to-consumer genealogical techniques used today, so it did not prove very useful. By 2019 however, genetic genealogy had finally advanced and succeeded where the legal system had failed,” said Fitzpatrick.

The alleged murderer, Patrick Nicholas, was arrested twice previously on sexual charges—once for first-degree rape and once for first-degree child molestation. The first time he was arrested for rape was in 1983, before CODIS was available; but the second time, he pleaded down to a gross misdemeanor, which did not require DNA collection as a felony would. Additionally, Patrick’s brother Edward was entered into CODIS for a convicted rape, but since familial searching is not practiced in Washington, Patrick escaped possible detection for the third time.

6th Place: DNA Exonerates and Implicates All At Once

The case selected as the last finalist of 50 worldwide entries illustrates the power of both traditional DNA testing and investigative genetic genealogy—especially when they work in conjunction with one another.

On July 7, 1985, 55-year-old Jane Hylton was found murdered in the home she just moved in to with her 13-year-old daughter Autumn Anker and her housemate Rickey Davis (20) and his girlfriend. An autopsy revealed Hylton was stabbed/cut 29 times, three of which were fatal. Additionally, a bite mark was found on her back-left shoulder. Investigators questioned Davis, his girlfriend, Anker and the three older boys she met and spent the day with, but no direct evidence was found and the case went cold.

In 1999, detectives re-opened the case and re-interviewed Dahl, who initially denied any more knowledge of the murder than she had back in 1985. Through the course of several interrogations between 1999 and 2005, Dahl eventually told detectives it was Davis who killed Hylton, but that she herself had bitten her mother during the attack. Davis was charged, tried, and convicted of murder in 2005—a murder he has continuously denied committing.

In 2012, the Northern California Innocence Project stepped in and commissioned DNA testing of several items from the crime scene, including the victim’s nightgown and fingernail scrapings. The DNA located on the victim’s nightgown near the bite mark matched DNA from one of the fingernail scrapings. But the profile was that of a male, so it could not be Dahl’s as she claimed.

The DNA profile was uploaded into CODIS, but no match was found. Then, it was uploaded into a genetic genealogy database. A relative of the unknown male subject was located, and further investigation revealed that the DNA profile belonged to Michael Green, one of the boys Anker had told detectives she met and hung out with the night of the murder.

With the new evidence, the murder charges against Davis were dismissed, while charges were filed against Green, who is now in custody awaiting trial.

Photo courtesy of Gordon Thomas Honeywell